1. Field of the Invention
This invention is an improved portable exhaust gas recirculation testing device, suitable for use in a wide variety of motor vehicles.
2. Description of the Prior Art
Most automotive vehicles of recent manufacture are equipped with engine emission control systems utilizing exhaust gas recirculation (EGR) valves. The EGR valve directs a portion of the motor vehicle's exhaust gas back through the engine's air intake system, thereby reducing nitrous oxides in vehicle exhausts. Vehicle EGR systems are subject to failure, resulting in decreased efficiency of the emissions control system. Because EGR system failures do not always produce a noticeable degradation in the performance of the vehicle, such failures often go unnoticed. Under these circumstances, the affected automobile appears to operate correctly, while producing a higher than acceptable level of exhaust gas emissions.
Many government regulatory agencies now impose strict limits on the amount of certain emissions which can be present in motor vehicle exhaust gases. To insure compliance with these emission requirements, government agencies frequently impose a periodic inspection requirement on motor vehicles, mandating annual evaluation of the motor vehicle exhaust to determine whether or not it is within the limits prescribed by the appropriate regulation or statute.
Vehicle emissions testing is frequently performed by a wide variety of automobile service facilities. These may include the repair facilities of authorized motor vehicle distributors, as well as independent service stations and repair shops. In some states in the United States, exhaust gas recirculation system testing requires a detailed diagnosis of the function of exhaust gas recirculation solenoids which control the operation of exhaust gas recirculation valves.
A variety of diagnostic devices for EGR systems have been proposed and implemented. Often, EGR testing is performed in the vehicle, as taught by Sawamoto et al., U.S. Pat. No. 5,140,961. Additionally, simple portable devices for manually activating and deactivating the exhaust gas recirculation valves have been used.
Many existing motor vehicles are not equipped with on-board diagnostic EGR testing, and in many cases, the on-board diagnostic systems do not perform tests suitable for the certification of EGR systems operations as required by government regulation and statute. Further, the simple portable testing devices heretofore used are typically incapable of operating in the test environment for a wide variety of motor vehicles, and fail to provide feedback to the test operator to verify that the operation of the EGR valves has been complete.